DESCRIPTION: Engineering a Human Physiomimetic Islet Microsystem Type 1 diabetes mellitus, an autoimmune disease resulting in destruction of the insulin- producing pancreatic beta cells, is one of the most common and costly chronic pediatric diseases. A significant impediment to understanding disease pathology and the development of cellular replacement therapies for Type 1 diabetes is the inability to sustain mature human beta cells in culture. In this proposal, we seek to engineer physiomimetic 3D niches within microfluidics devices for maturation, maintenance, and monitoring of human beta cells via the convergence of technologies from stem cell biology, matrix engineering, micro/nano fabrication, and microsensors. The microfluidic devices will connect to universal docks and provide intimate control over the cellular microenvironment by independent and simultaneous modulation of liquid and gas phases, multiparameteric monitoring, and assessment of cellular readouts and samplers for off-line biochemical analyses. With this degree of control, the effect of various niche parameters on human islet maintenance and generation of mature islets from human pancreatic precursors can be clearly delineated. Of particular interest in this application are the contributions of the physiological and extracellular matrix environment on islet health and maturation. Physiological oxygen, a critical parameter in steering pancreatic progenitor differentiation towards endocrine lineage, can be intimately modulated on the microscale via the control afforded by the microfabricated platform. Further, systematic evaluation of the contributions of matrix components on promoting islet health and directing islet differentiation within controlled 3D niches is feasible via tailored presentation of native extracellular matrix components. The ultimate goals of this proposal are twofold: 1) engineer a microfabricated device and dock system capable of providing microscale control of soluble and physiological conditions and agile assessment of multiple functional readouts in an enclosed, long-term culture system; and 2) utilize this innovative platform to systematically delineate critical factor capable of supporting both human islet maintenance and maturation of islet-like structures from human pancreatic progenitor cells. The project builds on recent breakthroughs by our team in creating microphysiological systems for other organ systems, engineering perifusion systems, matrix engineering, recreating oxygen controlled microenvironments, and progenitor differentiation. As such, the multidisciplinary consortium assembled herein is well poised to address these grand challenges.